Alumina (Al2O3) and alumina-containing compositions are used in many articles of manufacture. In many of its applications alumina is used in the form of small, somewhat spherical particles with high specific surface area (m2/g) as a support medium for even smaller particles of a catalyst metal or material. The alumina support particles provide a durable base for the function of the catalyst material.
Vehicle exhaust systems use catalytic converters to treat unburned hydrocarbons (HC), carbon monoxide (CO) and various nitrogen oxides (NOx) produced from the combustion of hydrocarbon fuels in the engine. A typical catalyst comprises one or more noble metals dispersed on high surface area alumina carrier particles. Often the alumina particles are mixed with particles of another oxide, such as ceria or lanthana, for oxygen storage during exhaust treatment.
Recently, one-dimensional (1D) nanostructures have attracted considerable interest in catalysis fields due to their large specific surface area, high sensitivity and activity, which promise improved catalytic efficiency. Provided that a hybrid of alumina and cerium (or other rare earth element) can be made as a one dimensional nanostructure, the efficiency and durability of the alumina/ceria based three-way catalyst may be significantly enhanced. Currently, wet chemical methods have been widely applied in three-way catalyst production, including sol-gel, hydrothermal, microemulsion methods and so on. However, it still remains a challenge to generate well crystallized, one-dimensional, Ce-doped alumina nanostructures using the conventional wet chemical methods.
It is an object of this invention to provide a method for making crystalline alumina nanowires in which the alumina structures may contain or carry one or more rare earth elements.